1. Field of the Invention
The present invention relates generally to vehicle radiator caps of the type commonly associated with radiator fluid reservoirs for internal combustion engines. More particularly, the present invention relates to an improved vehicle radiator cap design having a reduced number of component parts and other novel and useful features of construction which enhance the performance and reliability of the cap, while appreciably reducing the manufacturing costs for the cap.
2. Background Art
Internal combustion engines which are liquid cooled incorporate radiators coupled to the engines to dissipate heat generated by the engine. As the radiator fluid passes through the radiator, heat is given off to the environment, and the now relatively cooler fluid is returned to the engine. Radiator caps are designed to engage with the filler neck of the radiator and perform a number of specific functions, the primary one being to provide a seal for the filler neck of the radiator fluid reservoir.
After the engine is started, the operating temperature of the engine increases, causing an increase in the pressure in the radiator. Radiator caps typically include a pressure relief valve which is normally closed to prevent the escape of radiator fluid when normal pressures are generated within the radiator. However, when the pressure in the radiator build up beyond the strength of the pressure relief spring, the valve is pushed open and radiator fluid escapes past the pressure relief valve. In most modern automobiles, the overflow radiator fluid flows out of a port in the radiator filler neck into an overflow tank. The overflow fluid or coolant is returned to the tank upon the development of vacuum or subatmospheric pressure within the radiator after the engine has cooled. Radiator caps also typically have a vacuum relief valve which opens in response to the development of subatmospheric pressure within the radiator in order to facilitate the return of coolant from the overflow tank to the radiator reservoir proper. In addition to performing these functions, a radiator cap should also provide a free turning crown such that during the manual engagement of the cap with the filler neck, the primary sealing element which makes contact with the filler neck is not scuffed as the crown is rotated into engagement with the filler neck, as repeated scuffing causes a weakening and deterioration of the sealing element.
Workers in the art have produced a number of radiator cap designs to accomplish these basic tasks, representative examples being U.S. Pat. No. 3,878,965, issued to Crute and U.S. Pat. No. 4,185,751, issued to Moore et al. However, the prior art designs such as the Moore et al. and Crute patents require as many as 13 or more individual components to be manufactured and assembled in order to make a functioning cap. For example, the Crute patent provides a free turning crown, but the design requires an additional, discrete member to be retained by a central rivet, thus increasing the design's cost and complexity. As radiator caps are typically manufactured in very large quantities to meet the demands of the automotive industry, there is a genuine need for improvements in design which translate into reduced manufacturing costs and simplification and ease of assembly, while improving the performance and reliability of the design. Moreover, as radiator caps function under conditions of high temperature, pressure and humidity, they are subject to mechanical stresses which, over time, can cause metal and plastic parts to creep, that is, to become distorted. Thus, there is a need for a radiator cap design which reduces the stresses on the components, thereby making the radiator cap more durable and reliable.
Accordingly, it is an object of the present invention to reduce the costs associated with the manufacture of a radiator cap, while improving the reliability and performance of the cap.
A further object of the present invention is to provide a radiator cap of increased ease of manufacture and assembly having a reduced number of component parts.